After the installation of the four Unit Telescopes of the VLT in the years 1998 till 2000 more than 1.5 million active optics measurements and corrections have been performed. Since all active optics data are logged together with various environmental parameters (external seeing, temperatures, wind, etc.) extensive statistical studies of the dependence of the optical performance of the telescope on the external parameters can be made. Improvements of the functionality and the performance of the telescopes include the use of a Kalman filter in the Active Optics correction loop and the possibility to adjust actively the plate scale of the telescope.